Process for treating cellulosic material



NOV- 22, 1932 c. D. AlNswoRTH PROCESS FOR TREATING CELLULOSIC MATERIAL Filed Aug. 14, 1923 Patented Nov. 22, 1932 man CHESTER D. AINSWORTH, OF WOLLASTON, MAH'SACHUSETTS PROCESS FOR TBCEATING CELLULOSIG MATERIAL Application led August14, 1923. Serial No. 657,441.

This invention relates to and has for its object a novel process for the removal of the gums, as the resins and sugars and the like from a material containing them, as a fibrous cellulosic material, as wood and the like, and,

particularly, without destroying the structure or formation of the material.

The invention is particularly concerned with, although not limited to, a process of treatment of wood for violins and other musical or acoustic instruments, or the instruments themselves, or finished parts therefor, by which the wood is caused to become more resonant and the tonal qualities thereof are enhanced.

A wood which enters into the construction of a violin, for instance, for excellence of tone, is required to vibrate easily over the entire note range of the instrument and to respond purely and with practically uniform intensity to notes of uniform intensity over the entire note range. In addition to response to the fundamental tone, it should be capable of vibrating in pleasing overtones whereby to produce the characteristic violin tone. Ordinarily the more numerous the harmonious overtones to which the wood will respond, the better is the Violin considered.

The ease with which the wood of a violin may respond to the string vibrations, andthe number and harmoniousness of the overtones, other things being equal, depends upon the amount of loading oftthe wood with its natn ural resins or sugars. The resins and sugars 5 act to damp the vibration of the wood, whereby it may respond only with difficulty to the vibration of the string, and cause the wood to vibrate unequally in localized portions thereof, therebyto set up displeasing overtones. Resins and sugars are necessarily present in wood and the difference between agood and a poor violin, otherwise having uniform characteristics, may be measured by w the gum content of the Wood entering into the construction of the violin, the good violin having a smaller `gum content of its wood than the poor violin, or a more uniform dstribution of gum. r An object of this invention is an improved "o process of treating a material, as wood or other cellulosic material to de-gum it, or to remove a substantial portion of the resin or sugar or other undesirablecontent therein, without destroying the structure of the material and, also, without altering the configuration or appearance of the material in any harmful manner.

A further objectis a process of treating wood for a violin or other acoustical instrument to improve the tonal qualities of the instrument in which the wood is incorporated.

A further object is a process of treating the complete instruments, orfinished parts therefor, to improve the tonal .qualities thereof, without altering the configuration or appearance of the instrument, or parts, in any harmful manner.

A yet further object is generally to improve the processes for de-gumming. cellulosic material.

In brief, -my improved process consists in subjecting the cellulosic material, for the degumming thereof, as the removal of resins or sugars therefrom, to the action of an electric field of a suitable nature, and for a suitable period of time,4and preferably at the same time subjecting the material to a. reduced ambient gaseous pressure. Preferably the electric field is adapted to be such as to producean ionic discharge, or an arc stream, in

the vicinity of the cellulosic material and in a vacuum of a few millimeters pressure, in which vacuum the cellulosic material is contained. 8 Fig. 1 is'a diagrammatic illustration of the apparatus for carrying out my process:

Fig. 2 is a modified arrangement of Fig. 1. Fig. 3 is a further modification, and illustrating an apparatus especially adapted for .the treatment of wood for the manufacture v of paper pulp.

vIn carrying out my process, as one adaptation thereof, I may enclose the w`ood piece 10 r to be treated, which piece here shown may 9 be the base bar of a violin, for instance, in a closed receptacle as the bell jar 11, which jar may rest upon the plate 12 of an air pump 13.

' Said air pump is adapted to exhaust said bell jar to a suitably low pressure, as a Crookes to pass a given current through the gas becomes greater. The converse also apparent- 1y holds true. For a large amount of electrical power, the vacuum may be less than for a lesser amount of electrical power, to carry .out the process to the same degree in the same time. Preferably, however, the vacuum is adapted to be such as to lower the oxygen f said terminals.

content -of the air in the receptacle, or bell jar, to such a degree that the wood undergoing treatment will not be oxidized by the action of the electrical field. If the atmosphere in the receptacle is inert, that is, does not contain a gas capable of acting on the wood in -any harmful manner, the pressure within the receptacle may be materially different than with an atmosphere having an oxygen content. K

The bell jar 11 may be provided with a terminal 14 which extends into the bell j ar and said terminal is adapted to be connected with a source of high potential, as the secondary winding of a transformer or induction coil 15. Said secondary winding may be connected with a second terminal of said'bell jar andA said second terminalmay comprise the plate 12 of the vacuum pump, as shown. The two terminals are adapted to be spaced apart a suitable distance and the wood piece 10 is adapted to be disposed between or' in the vicinity of said terminals in position to be acted on by the electric field set un between As here shown, the transformer or induction coil 15 is provided with .an interrupter 16 in its primary circuit and said primary circuit may be connected to 'a" suitable source of alternating current. Said interrupter 16 may be synchronized with the 'frequencyof the alternating current whereby to produce a predominating direct potential at the secondary terminals. My Iprocess may be carried out satisfactorily with either an alternating potential or a direct potentialan for commerci al purposes,l an alternatingpotential is preferable. When an alternating potential is to be used, the coil 15 may be replaced by a high potential. transformer of any desirable type. The precise potential at which my process is carried out will vary with the spacing of the .discharge terminals 14 and 12 and the degree of vacuum existing between said terminals but the potential should preferably be sufficient to cause an appreciable ionic current fiow or arc stream or discharge between said terminals.

The wood piece 10 to be treated is placed in position to be acted upon by the electric field set up between `said terminals andpreferably, said wood piece 10 is disposed beporting member and also with the upper.

terminal 14, whereby to supportthe wood piece from, andelectrically connect it with, said terminal. A second conductor 20 may 'lay be connected with thev lower supporting member and be in contact with, or in proxim-V ity to the lower terminal 12.

In carrying out my process, in the preferred manner, a high potential is applied to the terminals 14 and 12 and the receptacle 11is evacuated by the pump 13. The degree of evacuation may be variable andY may depend upon the amount of electrical power available and upon the electric potential. Preferably an ionic discharge or arc stream should` take place between they electrodes or terminals of the receptacle, and the degree of evacuation is adapted to be such as to permit such discharge. So long as a discharge takes place, the .character thereof, as governed by the degree of evacuation, does not appear to be highly important. Under a .certain vacuum the discharge may beconfined to a more or less broad band or arc stream between the electrodes, or the supporting-members 18, and at one side of thel wood piece 10, as illustrated at 25, Fig. 1. At a higher vacuum, the discharge stream maycompletely enclose and surround the 'wood piece 10 and the discharge stream may show the characteristic poten tial bands of an electric discharge in a high vacuum.

As the wood piece 10 undergoes treatment it will be noted that the surface of the wood usually assumes a brighter appearance and inally shines and glistens when a beam of light is thrown on it. v Sap or resinpockets, which might be contained in the wood below the surface and invisible priorto the treatment, are caused to stain the wood at the surface as the resln or sugar therein is .driven may be equally applicable to other uses and' overtones, and more in minute particles and is or may be deposited on the walls of the receptacle and the electrodes. At intervals microscopic nodules or stalactites of resin or sugar, which may be composed of small resin or sugar particles coherently united under the heat of the reaction although the wood piece may not rise in temperature more than a few degrees, appear on the Surface `and appear to bel inclined toward the arc stream or the terminals, depending upon the location ofthe nodules, and are or may be iinally disintegrated and disappear. The completion of the reaction is indicated, to the practiced observer, when the surface of the wood takes on a shining and satiny appearance. Different woods may have different appearances when the process is practically completed, which appearances are readily recognized with practice. The diminution or cessation of formation of gum nodules and discharge of gum particles is also an indication of the practical completion of the process, although more diicultly observable.

The time of the process varies with the dimensions and character of the wood piece, a hardwood usually requiring a longer treatment than a soft wood. Ordinarily, for small pieces of wood, such as the tops of violins, the process is practically complete at the end of half an hour with say one hundred watts of electrical energy at say, seven thousand volts. It may be found desirable to operate the vacuum pump at intervals, to maintain the vacuum during the treatment.

The treated wood, when suitably supported and struck, to cause it to vibrate, gives oil' a predominant note which usually is distinctly higher than its predominant note prior to the treatment. The tone persists for a much greater period of time and has more harmonious overtones, than the untreated piece; all of which are readily recognized by an experienced observer.

The action of the process appears to set up a force which acts on the gum particles which are finely distributed through the Wood, to drive them to the surface and dispel them from the surface throughout the receptacle. where they will be deposited on the walls of the receptacle and the electrodes. The deposit appears to be greatest in the vicinity of the more positive electrode.

While I have described my invention mainin connection with an improved wood for vio ins and other acoustic instruments; it materials. In Fig. 3, for instance, I have illustrated an apparatus adapted for treating a cellulosic material, such as wood chips, for the removal of the gums, to prepare the wood chipsfor paper making.

' The receptacle 30 may be made of steel, for instance, and have an insulating lining 31 therein. Insulated electrodes 32 may extend into the receptacle and be connected with a suitable source of Velectrical power, as the high tension transformer33. The receptacle may be evacuated to a suitable degree by the vacuum pump 34. Wood chips, or other suitable material, may be introduced into the receptacle through the upper manhole 35 and packed between the electrodes, and the' treated material may be removed through the lower manhole 36. As thus arranged the arc stream will be through the material.

With the above process, the structure or form of the wood piece is not altered in any manner.

I claim: l

l. The method of removing gum from cellulosic material which consists in subjectmg the cellulosic material to the influence of an electrostatic field having such high potential and under such condition as to act on and dispel gum from the material without destroying the latter.

2. The method of removing gum from cellulosic material which consists in subjectlng the cellulosic material to the influence of a reduced gaseous pressure and an electrostatic field having such high potential as to act on and dispel gum from the material.

3. The method of treating cellulosic material to extract the gum therein which consists in subjecting the material to the influence of a high potential electrostatic field and an ionic discharge, under conditions to extract the gurln without destroying the cellulosic materia 4. The method of treating cellulosic material to extract the gum thereln which consists in subjecting the material to the combined influence of a vacuum and a high potential electro-static field and an ionic discharge in the vacuum.

5. The method of treating wood to increase the resonant quality thereof which consists in subjecting the wood for a substantial period of time to the influence of a high potential electrostatic field under such condition as to prevent destruction of the wood. f

6. The method of treating wood to increase the resonant quality thereof which consists in subjecting the wood for a. of time to the influence of resure and a. high potential electrostatic 7 The method of treating wood which comprises establishing about the wood a high potential arc stream in a substantially inert atmosphere.

8. The method of treating wood which comprises establishing about the wood a high potential arc stream in an atmosphere of reduced gaseous pressure.

9. The method of treating wood which comprises establishing about the Wood besu-bstantial period a reduced gaseous' tween spaced electrodes a potential suiciently high to produce an are stream in a vacuum, and maintaining said potential until the gum is dispelled from the wood.

10. The method of treating wood which comprises establishing between spaced electrodes and about the Awooda high potential arc stream in an inert atmosphere.

11. The method of treating .wood which comprises placing wood in an inert atmosphere between spaced electrodes, establishing a high potential arc stream between said electrodes, and maintaining said arc stream until the gum is dispelled from the Wood.

12. The method of removing normally solid mobile dielectric particles from fibrous material containing them which consists in subjecting said material to the influence of an electrostatic field having such high potential and under such conditions as to dispel said mobile particles from said material without destroying the latter.

13. The method of 'removing normally solid mobile dielectric particles from fibrous material containing them which consists in subjecting said material to the combined influence of a vacuum and a high potential electrostatic field and an ionic discharge in the vacuum. Y

In testimony whereof, I have signed my name to this specification.

CHESTER D. AlNSWORTH. 

